Electrosurgical instrument

ABSTRACT

An electrosurgical instrument of the invention comprises a body (3) and, arranged coaxially, a passive electrode (2) and an active electrode (1), of which the outer electrode is associated with the body (3) and the central electrode is traversable with respect to the outer electrode (2). The instrument is provided with a power actuator and a device for cleaning the central electrode (1) of carbon deposit, the device being interposed between the electrodes (1, 2) and being made as an insert of an insulating material and provided with a through hole to suit the diametrical size of the central electrode (1) which extends through the hole. The electrode (1) is rigidly coupled to the power actuator for being traversable with respect to the hole.

TECHNICAL FIELD

The present invention relates to medical engineering and morespecifically it concerns electrosurgical instruments.

BACKGROUND ART

Known in the present state of the art is an electrosurgical instrumentwhich is comprised of two electrodes, i.e., a small-area activeelectrode serving as the working electrode proper, and a larger-areapassive electrode ( cf. the paper entitled "Application of biactivebipolar electrodes in electrosurgery" by S. M. Shamraevsky et al. in thejournal "Vestnik khirurgii imeni I. I. Grekova", No. 1, pp. 66-67 issuedin 1971) (in Russian).

It is common practice that the passive electrode is bandaged to thelateral surface of the left thigh, or put under the patient's back,whereas the active electrode is used to carry out the surgical procedureinvolved. In this case the current field lines are dispersed in thetissues, thus concentrating in low-resistance areas and passing by thosefeaturing poor electric conductance.

Use of the aforesaid instrument involves no clear-cut borderline betweencoagulated and sound tissue and may inflict damage to some organs andtissues located distantly of the place of application of the activeelectrode. In addition, orientation of the coagulation process as fordirection and depth is impeded, and burns are likely to occur at theplace of the passive electrode application.

One more prior-art electrosurgical instrument is known to comprise abody and coaxial electrodes of which the outer passive one is rigidlyheld in the body, while the central active electrode is traversable withrespect to the outer electrode (cf. U.S. Pat. No. 4,043,342, Class A 61B 17/32 published in 1977).

The instrument enables the current field lines to be concentrated at theactive electrode situated in close proximity to the passive electrode,whereby the working zone is reduced drastically which makes practicableto carry out single-point coagulation or fine dissection of a tissue,e.g., in layer-by-layer excision of the gastric wall.

However, when surgery is performed by the aforesaid heretofore-knowninstrument the latter is liable to get out of order rather quickly dueto carbon deposition on the active electrode, which thus interferes withfurther surgical procedure. Therefore the instrument is to be cleaned ofcarbon deposit repeatedly in the course of surgery, which is carried outmanually and involves withdrawal of the instrument from the workingzone, thus prolonging the operating time and complicates the surgeon'sjob.

DISCLOSURE OF THE INVENTION

The principal object of the invention is to provide an electrosurgicalinstrument which, when applied for carrying out limited single-pointcoagulation or fine dissection of a tissue would incorporate means forautomatic removal of carbon deposit from the active electrode in thecourse of surgery.

Said object is accomplished due to the fact that an electrosurgicalinstrument, comprising a body and coaxially arranged a passive and anactive electrode of which the outer one is associated with the body,while the central electrode is traversable with reference to the outerelectrode, according to the invention, is provided with a mechanicalactuator and a device for cleaning the central electrode of carbondeposit, fashioned as an insert made of an insulant and interposedbetween the electrodes, said device having a through hole to suit thediametrical size of the central electrode which passes through said holeand is rigidly coupled to the mechanical actuator for traversingrelative to said hole.

The mechanical actuator may be so constructed as to impart reciprocatingmotion to the central electrode lengthwise the axis of said hole.

It is expedient that the central electrode be shaped as a needle locatedin the hollow space of the cylinder-shaped body at the end of which theouter electrode is provided, said outer electrode being shaped as a nutthread-joined with the body and accommodating an insert made as aspring-actuated ball having a centre hole and serving as a device forcleaning the central electrode of carbon deposit.

It is also practicable that the mechanical actuator be so made as toimpart rotation to the central electrode about its longitudinal axis andthat the central electrode be provided also with a means for itstraversing along the axis of said hole.

It is desirable that the insert be shaped as a collet grip.

An electrosurgical instrument according to the present inventionprovides for limited single-point coagulation and fine dissection oftissues accompanied by automatic cleaning of the active electrodeworking surface in the course of surgery. The electrosurgical instrumentmade according to the invention is capable of:

- cutting of tissues with the rotary active electrode, whereby thelatter is efficiently cleaned by the tissue being dissected immediatelyin the course of surgery;

- reciprocating motion of the active electrode with respect to thecleaning device strictly along the electrode longitudinal axis, whichenables the instrument to be cleaned without retracting its workingportion from the line of cut, this being impacticable with the knowninstrument due to incessant deviation of the active electrode end fromtrue axial direction in the course of cleaning;

- efficient cleaning of the active electrode surface with the air of thecleaning device which, unlike the heretofore-known one, is not liable tolose its useful properties due to attrition, since its permanent forcingagainst the surface being cleaned is ensured.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows the invention will now be disclosed in a detaileddescription of some specific exemplary embodiments thereof withreference to the accompanying drawings. According to the invention, inthe drawings:

FIG. 1 is a general longitudinal sectional view of an electrosurgicalinstrument;

FIG. 2 is a view, facing arrow A, of the working portion of theelectrosurgical instrument of FIG. 1;

FIG. 3 is a view of an area B in FIG. 1 showing the central electrode ina retracted position;

FIG. 4 is fragmentarily cutaway a view of FIG. 1 showing an embodimentwith the insert made as a collet grip;

FIG. 5 is a scaled-up section taken along a line V--V in FIG. 4;

FIG. 6 is a sectional view of an embodiment of the electrosurgicalinstrument provided with a rotary motion mechanical actuator;

FIG. 7 is a section taken along a line VII--VII in FIG. 6; and

FIG. 8 is a section taken along a line VIII--VIII in FIG. 6.

BEST MODE OF CARRYING OUT THE INVENTION

The electrosurgical instrument comprises an active central electrode 1(FIGS. 1, 2, 3) shaped as a needle, and an outer passive electrode 2arranged coaxially with the electrode 1 and made as a nut which isthread-joined with the end of a cylinder-shaped body 3. The interiorspace of the body 3 accommodates the electrode 1. In addition, theinstrument incorporates a power drive comprising an electric motor 4whose shaft mounts a crank 5 and a bearing 6 secured on the latter. Theouter race of the bearing 6 carries the end of the active electrode 1which is rigidly held to it and has a springy loop 7. The other(working) end of the active electrode 1 passes through the hole in aninsert, which is essentially a ball 8 in the embodiment underconsideration, made of an insulating material and inperposed between theelectrodes 1 and 2 inside the nut and forced to it with a spring 9. Theball 8 functions as a device for cleaning the electrode 1 of carbondeposit. The hole in the ball 8 is equal in size with the diameter ofthe needle-shaped electrode 1. A housing 10 of the electric motor 4 isassociated with the cylinder-shaped body 3 through an adapter 11. Ametallic spring 12 is provided for locking the nut (of the electrode 2).Diathermic current is supplied to the electrodes 1 and 2 through currentleads 13 and 14, respectively from a diathermic current source 15.Current leads 16 and 17 are provided for connection of the electricmotor 4 to a power source (omitted in the Drawings).

FIGS. 4 and 5 illustrate an embodiment of the electrosurgical instrumentfeaturing the insert made as a three-jaw collet grip 18 whose jaws areloaded with springs 19. The collet grip 18 is made of a dielectricmaterial.

In an alternative embodiment of the electrosurgical instrumentrepresented in FIGS. 6, 7, 8 unlike the embodiments shown in FIGS. 1 to5, the active central electrode 1 is associated, through a coupling 20,to an output shaft 21 of the electric motor 4 from which rotation isimparted to the electrode 1. To this end, longitudinal slots in thecoupling 20 accommodate the arms 22 of a spider 23 secured at thenonworking end of the active electrode 1. The insert functioning as thedevice for cleaning the electrode 1 is fashioned in this embodiment ofthe instrument as a collet grip 24. Thus, the working end of the activeelectrode is clamped in the collet grip 24 which consists of three jaws25 made of a dielectric material, a step bearing 26 resting upon thejaws 25, a step bearing 27 resting upon an annular shoulder 28 providedin the interior of the cylindrical body 3, and the spring 9 interposedbetween the step bearings 26 and 27. Collars 29 and 30 are provided inthe central portion of the active electrode 1, between which a slidablebushing 31 is set, said bushing being provided with an annular ridge 32at its end facing the electric motor 4. A return spring 33 is fittedbetween the annular ridge 32 of the slidable bushing 31 and the housingof the electric motor 4, said spring forcing the bushing 31 against thecollar 29. The slidable bushing 31 is provided with two journals 34accommodated in a fork 35 of a lever 36 articulately connected to ahandgrip 37 of the instrument through a pivot 38. The handgrip 37 isrigidly attached to the cylinder-shaped body 3.

It is the electric motor 4 with the output shaft 21, the coupling 20 andthe spider 23 that provide for continuous rotation of the activeelectrode 1. The lever 36, the slidable bushing 31 with the annularridge 32 and the journals 34, the collars 29, 30 and the return spring33 taken together establish the means for traversing the activeelectrode 1 along the axis of symmetry (hole) of the collet grip 24.

The electrosurgical instrument of the invention operates as follows.

Prior to surgery the electrodes 1 and 2 are set in relative position toeach other so as to suit the required depth of penetration of the activeelectrode 1 (FIGS. 1, 2, 3) in the tissue being operated upon, which isattained by screwing the nut onto the body 3 until the required mutualarrangement of the electrodes is attained. This done, the nut is lockedin place with the spring 12.

The working end of the active electrode (FIGS. 1, 2, 3) and the circularportion of the passive electrode 2 are so positioned at the place ofsurgery that the active electrode 1 is situated at a preset point or onthe line of cut and that the passive electrode 2 is in a reliablecontact with the living tissue surrounding the active electrode 1,whereupon diathermic current is supplied to said electrodes 1 and 2 fromthe source 15 through the current leads 13, 14.

When a single-point microsurgery is performed, e.g. on a cerebral tumor,the active electrode 1 destroys the living tissue and penetratesthereinto for a depth depending on the amount of overhang of its workingend relative to the passive electrode 2. Concurrently with thepenetration of the active electrode 1 into the living tissue, thereoccurs electrocoagulation of the blood and lymphatic vessels, wherebythe surgical procedure is a bloodless one. Once the tumor has beendestroyed the instrument is withdrawn from the operative zone. Shouldcarbon deposit be found to have formed on the active electrode 1, theelectric motor 4 is switched on with the result that the electrode 1receives reciprocating and oscillating motions, thus being cleaned ofcarbon deposit while interacting mechanically with the edge and faces ofthe hole in the ball 8. FIGS. 1 and 3 illustrate the electrode 1 whilein its extreme positions, respectively.

When performing fine dissection of a tissue, e.g., in layer-by-layerexcision of the gastric wall, penetration of the active electrode 1 intothe living tissue is followed by moving the instrument along the line ofcut, thus dissecting, e.g., the gastric mucosa bloodlessly. To removecarbon deposit from the surface of the active electrode 1 as fast as itis formed, the electric motor 4 is switched on periodically to clean theelectrode surface of carbon deposit. As a rule, the cutting processinvolved in microsurgical procedures is not combined with the cleaningof the active electrode, i.e., the instrument, while being cleaned, isnot traversed along a preset line of dissection. However, the instrumentneed not be withdrawn from the dissection zone for cleaning.

The embodiment of the electrosurgical instrument illustrated in FIGS. 4and 5 operates in the same way as described hereinbefore with the soleexception that the collet grip 18 provides for better cleaning of theelectrode 1 of carbon deposit within a shorter lapse of time.

The electrosurgical instrument represented in FIGS. 6, 7, 8 operates asfollows.

Prior to surgery the depth of penetration of the electrode 1 into theliving tissue is preset, in a way similar to that described above, thatis, by changing its position relative to the passive electrode 2 bymoving the latter on the thread of the body 3. Then the electric motor 4is energized with the result that rotation of the output shaft 21 of theelectric motor 4 is translated, via the coupling 20 and the spider 23,to the needle of the active electrode 1.

While rotating the active electrode 1 destroys the living tissue andpenetrates thereinto for a depth which depends on the amount of overhangof its working end with respect to the passive electrode 2. Concurrentlywith the penetration of the electrode 1 into the living tissue, thereoccurs electrocoagulation of the blood and lymphatic vessels, wherebythe surgical procedure is carried out bloodlessly.

During surgery the continuously rotating needle of the active electrode1 self-cleans due to a permanent sliding contact with the compactedliving tissue. However, an additional mechanical cleaning of the activeelectrode 1 is to be resorted to in the case of a prolonged surgicalprocedure, or when dissecting badly bleeding tissues, use being made ofa device imparting reciprocating motion to the active electrode 1 withrespect to the axis of symmetry of the collet grip 24. To this aim oneshould periodically depress the lever 36, which, while turning about thepivot 38, urges the journals 34 of the slidable bushing 31 to move byvirtue of the fork 35. The annular ridge 32 of the bushing 31 pressesupon the collar 30 provided on the active electrode 1, thus compressingthe return spring 33 and causing the needle of the active electrode 1 tomove towards the electric motor 4. As a result, the arms 22 of thespider 23 slide along the longitudinal slots of the coupling 20, and theworking end of the active electrode 1 is pulled, while rotating, throughthe jaws 25 of the collet grip 24, thus getting rid of carbon depositefficiently. The return stroke of the active electrode 1 (i.e., awayfrom the electric motor 4) is actuated by the return spring 33 whichforces the slidable bushing 31 against the collar 29 as soon as thelever 36 is released. Thus, the lever 36 should be given severaldepressions to completely clean the instrument of carbon deposit.

It is due to the active electrode 1 traversing strictly along itslongitudinal axis that mechanical cleaning of the instrument can becarried out without withdrawing the instrument from the operative zone.Continuous rotation of the active electrode 1 promotes its efficientself-cleaning by the compacted tissue and simplifies much itspower-assisted cleaning with the aid of the collet grip 24. Use of thecollet grip 24 provides for continuous reliable contact of the jaws 25with the surface being cleaned of the active electrode even when thejaws 25 are somewhat worn.

Reciprocating motion of the active electrode 1 can be still more easedcompared with the aforedescribed construction, when the active electrode1 is rigidly coupled to the output shaft 21 of the electric motor 4, andthe housing of the electric motor 4 is traversed by means of the leverand the return spring 33 (such an embodiment being omitted in theDrawings).

INDUSTRIAL APPLICABILITY

The electrosurgical instrument of the invention can find widespreadapplication in microsurgery, as well as for performing bloodless plasticsurgery on the gastro-intestinal tract, urinary system, the lungs, andsome other organs.

We claim:
 1. An electrosurgical instrument, comprising:a cylinder-shapedbody having an interior; a passive outer electrode mounted to an end ofthe cylinder-shaped body in coaxial relation therewith and made as a nutthread-joined with the body; an active central electrode shaped as aneedle located in the interior of the cylinder-shaped body coaxiallywith the outer electrode and traversable with respect to the outerelectrode; means for cleaning carbon deposits from said centralelectrode, said means including an insert made of an insulating materialand accommodated inside the outer electrode, the insert being made as aspring-actuated ball having a central hole through which the centralelectrode is passed, the ball hole having an axis and a diameter equalto the diameter of the central electrode; and a power actuator rigidlycoupled to the central electrode to impart reciprocating motion to thecentral elctrode along the axis of the ball hole.
 2. An electrosurgicalinstrument, comprising;a cylinder-shaped body having an interior; apassive outer electrode mounted to an end of the cylinder-shaped body incoaxial relation therewith; an active central electrode located in theinterior of and coaxial with the cylinder-shaped body and traversablewith respect to the outer electrode; means for cleaning carbon depositsfrom said central electrode, said means including an insert made of aninsulating material and accommodated inside the outer electrode, theinsert having a central hole through which the central electrode ispassed, the insert hole having an axis and a diameter equal to thediameter of the central electrode; a power actuator rigidly coupled tothe central electrode to impart rotational movement to the centralelectrode about its longitudinal axis; and additional means for causingsaid central electrode to traverse along the axis of said hole.
 3. Anelectrosurgical instrument, comprising;a cylinder-shaped body having aninterior; a passive outer electrode mounted to an end of thecylinder-shaped body in coaxial relation therewith; an active centralelectrode located in the interior of and coaxial with thecylinder-shaped body and traversable with respect to the outerelectrode; means for cleaning carbon deposits from said centralelectrode, said means including an insert made of an insulating materialand accommodated inside the outer electrode, the insert being made as acollet grip through which the central electrode is passed; a poweractuator rigidly coupled to the central electrode to impart rotationalmovement to the central electrode about its longitudinal axis; andadditional means for causing said central electrode to traverse alongthe axis of said hole.